Dequeue.cpp

#include<iostream>
using namespace std;
#define SIZE 5

class dequeue
{
    int a[10], front, rear, count;

public:
    dequeue();
    void add_at_beg(int);
    void add_at_end(int);
    void delete_fr_front();
    void delete_fr_rear();
    void display();
};

dequeue::dequeue()
{
    front = -1;
    rear = -1;
    count = 0;
}

void dequeue::add_at_beg(int item)
{
    int i;
    if (front == -1)
    {
        front++;
        rear++;
        a[rear] = item;
        count++;
    }
    else if (rear >= SIZE - 1)
    {
        cout << "\nInsertion is not possible, overflow!!!!";
    }
    else
    {
        for (i = count; i >= 0; i--)
        {
            a[i] = a[i - 1];
        }
        a[i] = item;
        count++;
        rear++;
    }
}

void dequeue::add_at_end(int item)
{
    if (front == -1)
    {
        front++;
        rear++;
        a[rear] = item;
        count++;
    }
    else if (rear >= SIZE - 1)
    {
        cout << "\nInsertion is not possible, overflow!!!";
        return;
    }
    else
    {
        a[++rear] = item;
    }
}

void dequeue::display()
{
    for (int i = front; i <= rear; i++)
    {
        cout << a[i] << " ";
    }
}

void dequeue::delete_fr_front()
{
    if (front == -1)
    {
        cout << "Deletion is not possible: Dequeue is empty";
        return;
    }
    else
    {
        if (front == rear)
        {
            front = rear = -1;
            return;
        }
        cout << "The deleted element is " << a[front];
        front = front + 1;
    }
}

void dequeue::delete_fr_rear()
{
    if (front == -1)
    {
        cout << "Deletion is not possible: Dequeue is empty";
        return;
    }
    else
    {
        if (front == rear)
        {
            front = rear = -1;
        }
        cout << "The deleted element is " << a[rear];
        rear = rear - 1;
    }
}

int main()
{
    int c, item;
    dequeue d1;

    do
    {
        cout << "\n\n****DEQUEUE OPERATION****\n";
        cout << "\n1-Insert at beginning";
        cout << "\n2-Insert at end";
        cout << "\n3-Display";
        cout << "\n4-Deletion from front";
        cout << "\n5-Deletion from rear";
        cout << "\n6-Exit";
        cout << "\nEnter your choice <1-6>: ";
        cin >> c;

        switch (c)
        {
        case 1:
            cout << "Enter the element to be inserted: ";
            cin >> item;
            d1.add_at_beg(item);
            break;

        case 2:
            cout << "Enter the element to be inserted: ";
            cin >> item;
            d1.add_at_end(item);
            break;

        case 3:
            d1.display();
            break;

        case 4:
            d1.delete_fr_front();
            break;
        case 5:
            d1.delete_fr_rear();
            break;

        case 6:
            exit(0);
            break;

        default:
            cout << "Invalid choice";
            break;
        }

    } while (c != 6);
    return 0;
}